1. Field of the Invention
The present invention relates generally to a Radio Frequency (RF) repeater array antenna and, more particularly, to a method and divider for efficiently dividing power between respective radiation elements of an array antenna.
2. Description of the Related Art
An RF repeater antenna generally includes a radiation element array for transmitting and receiving radio waves, a reflector disposed behind the radiation element array and configured to reflect radio waves, and a division circuit for equally dividing power and providing equally divided power to respective radiation elements. According to the typical characteristics of an antenna, the antenna has non-uniform radio wave intensity at the locations of respective radiation elements, and exhibits a radiation pattern that has developed back and side lobes due to the scattering of radio waves at the edge of a reflector and the like.
Due to the above-described phenomena, signal interference occurs between transmission and reception signals or between repeaters. Schemes for improving the Front to Back (F/B) and Front to Side (F/S) ratios of an antenna by suppressing undesired waves that generate back and side lobes have been proposed.
For example, the above-described schemes include a scheme using a multi-reflecting plate structure and a radio wave absorption body, and a scheme based on the arrangement of radiation elements and the adjustment of the intervals between elements. However, the first scheme has problems in that the scale, size, and weight of the entire antenna are increased and in that an auxiliary side lobe is generated in front of an antenna, so that it is difficult to realize an F/S ratio equal to or higher than 20 dB. Meanwhile, the second scheme has a problem in that the design of the arrangement of radiation elements, the design of the intervals between the radiation elements, and means for adjusting a radiation pattern are complicated, so that the design and implementation thereof are difficult.
As known from theory, an F/B ratio and an F/S ratio can be improved by relatively increasing power for the center patch of an array and relatively decreasing power for the side patch of the array. Meanwhile, in order to feed a large amount of power to the center of the array using a typical parallel feeding method, a low division rate is required, so that the width of a division pattern must be designed so that it is very small. For example, in the case where, in a typical 3×3 patch array shown in FIG. 1, 1:8 power division is performed for a dielectric substrate having a dielectric constant of 3.0 and a thickness of 0.8t, a pattern having a width equal to or less than 0.2 mm is required. For this reason, problems arise in that it is difficult to implement such a scheme and it is difficult to use the increased normal transfer capability of an antenna.